phoneNumbers is array of 10 digit phone numbers, where the first three digits, in parentheses, are area codes. Using red

Question

not sure how to go about this
```app.js
const phoneNumbers = ["(503) 123-4567", "(646) 123-4567", "(503) 987-6543", "(503) 234-5678", "(212) 123-4567", "(416) 123-4567"];
let numberOf503;
// numberOf503 should be: 3
// Write your code below
numberOf503= phoneNumbers.reduce((acc,number)=>number.substr(0,2)===503, 0);
```

Blake Larson · Answer

The substring function will return a string so you want to compare it to "503". substring(1, 4) gets the 3 numbers between the parentheses. Pretty sure this will pass this challenge.
javascript
numberOf503 = phoneNumbers.reduce((acc, number) => {
  if(number.substring(1, 4) === "503") {
    acc++
  }
  return acc;
} , 0);

I would definitely use filter for something like this though when you get to use what you want. Just easier to use and cleaner. That would be like this in future scenarios.
javascript
numberOf503 = phoneNumbers.filter((number) => number.substring(1, 4) === "503").length;

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Joe Mbome

Joe Mbome

phoneNumbers is array of 10 digit phone numbers, where the first three digits, in parentheses, are area codes. Using red

1 Answer

Blake Larson

Blake Larson